Flies
Flies are s with a pair of functional wings for flight and a pair of specialized hindwings called for balance. They are as an called Diptera, that name being derived from the Greek δι- di- "two", and πτερόν pteron "wings". The order Diptera is divided into two s (although one suborder is non- ), with about 110 divided between them; the families contain an estimated 1,000,000 , including the familiar , , , and ; , , , , and fruit fly. In contrast, common names of non-dipteran insects that have "fly" in their names are written as one word, e.g. butterfly, stonefly, dragonfly, scorpionfly, sawfly, caddisfly, whitefly. In practice, however, this is a comparatively new convention; especially in older books, names like "saw fly" and "caddis fly", or hyphenated forms such as and dragon-fly are widely used. In any case, non-entomologists cannot, in general, be expected to tell dipterans, "true flies", from other insects, so it would be unrealistic to expect rigour in the use of s. Also, exceptions to this rule occur, such as the , which is a true fly, and the , a type of .}} although only about 125,000 species have a published. The earliest fly fossils found so far are from the , about 240 million years ago; phylogenetic analysis suggests that flies originated in the , about 260 million years ago. Many insects, such as the , contain the word fly in their name, but are not Dipterans. Also, the word "fly" is sometimes used colloquially and non-scientifically as a name for any small flying insect: the term "true fly" is sometimes invoked to make clear the insect being referenced is a Dipteran. Flies have a mobile head, with a pair of large compound s, and mouthparts designed for piercing and sucking ( es, and ), or for lapping and sucking in the other groups. The suborder (from Greek, "thready-horns") have thin, long antennae; while the suborder (from Greek "short-horns") have short antennae. Flies have only a single pair of wings to fly; their arrangement gives them great maneuverability in flight. The hindwings (halteres) evolved into advanced mechanosensory organs, which act as high-speed sensors of rotational movement and allow them to perform advanced aerobatics. Claws and pads on their feet enable them to cling to smooth surfaces. The of flies consists of the eggs, , , and the adult. Flies undergo complete ; the eggs are laid on the larval food-source, and the larvae (which lack true limbs) develop in a protected environment, often inside their food source. The pupa in higher dipterans is a tough capsule from which the adult emerges when ready to do so. Flies have short lives: for example, the adult housefly lives about a month; the mayfly about a year. The source of nutrition for adult flies is liquified food, including . Flies are of considerable and human importance. They are important s, second only to the bees and their n relatives. They may have been responsible for the first plant in the Triassic. es are for , , , , , and other ; and , commensal with humans all over the world, spread food-borne illnesses. Flies can be annoyances, especially in some parts of the world where they can occur in large numbers, buzzing and settling on the skin or eyes to bite or seek fluids. Larger flies such as and cause significant economic harm to cattle. Blowfly larvae, known as , and other dipteran larvae, known more generally as s, are used as , as food for carnivorous animals, and in medicine for . are used as s in research. In culture, the subject of flies appears in religion, literature, cinema, and music. Phylogenetic tree |1= (phantom and primitive crane-flies) |2= (mosquitoes) }} |2= (net-winged midges, etc) |2= (gnats) |2= (drain flies, sand flies, etc) |2= (crane flies) |label2= |2= |1= (soldier flies, etc) |2= (stink flies, etc) |2= (horse flies, snipe flies, etc) }} }} |label2= |2= |2= (robber flies, bee flies, etc) |label2= |2= (dance flies, etc) |label2= |2= (in part) |2= (flat-footed flies, etc) |2= (hoverflies) |label2= |2= |1= (louse flies, etc) |2= (house flies, dung flies, etc) |2= (blow flies, flesh flies, etc) }} }} |2= (marsh flies, etc) }} }} }} }} }} }} }} }} }} }} }} }} }} }} Abbreviations used in the cladogram: * Cal= * Cyc= * Ere= * Mus= * Sch= * Tab= References Category:Tree of life